.. _ctags-lang-r(7):

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ctags-lang-r

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Random notes about tagging R source code with Universal Ctags

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:Version: @VERSION@

:Manual group: Universal Ctags

:Manual section: 7

SYNOPSIS

--------

| **@CTAGS_NAME_EXECUTABLE@** ... --languages=+R ...

| **@CTAGS_NAME_EXECUTABLE@** ... --language-force=R ...

| **@CTAGS_NAME_EXECUTABLE@** ... --map-R=+.r ...

DESCRIPTION

-----------

This man page gathers random notes about tagging R source code

with Universal Ctags.

Kinds

-----------

If a variable gets a value returned from a *well-known constructor*

and the variable appears for the first time in the current input file,

the R parser makes a tag for the variable and attaches a kind

associated with the constructor to the tag regardless of whether

the variable appears in the top-level context or a function.

Well-known constructor and kind mapping

============ ==================

Constructor kind

============ ==================

function() function

c() vector

list() list

data.frame() dataframe

============ ==================

If a variable doesn't get a value returned from one of well-known

constructors, the R parser attaches ``globalVar`` or ``functionVar`` kind

to the tag for the variable depending on the context.

Here is an example demonstrating the usage of the kinds:

"input.r"

.. code-block:: R

G <- 1

v <- c(1, 2)

l <- list(3, 4)

d <- data.frame(n = v)

f <- function(a) {

g <- function (b) a + b

w <- c(1, 2)

m <- list (3, 4)

e <- data.frame(n = w)

L <- 2

}

"output.tags"

with "--options=NONE --sort=no --fields=+KZ -o - input.r"

.. code-block:: tags

G input.r /^G <- 1$/;" globalVar

v input.r /^v <- c(1, 2)$/;" vector

l input.r /^l <- list(3, 4)$/;" list

d input.r /^d <- data.frame(n = v)$/;" dataframe

n input.r /^d <- data.frame(n = v)$/;" nameattr scope:dataframe:d

f input.r /^f <- function(a) {$/;" function

g input.r /^ g <- function (b) a + b$/;" function scope:function:f

w input.r /^ w <- c(1, 2)$/;" vector scope:function:f

m input.r /^ m <- list (3, 4)$/;" list scope:function:f

e input.r /^ e <- data.frame(n = w)$/;" dataframe scope:function:f

n input.r /^ e <- data.frame(n = w)$/;" nameattr scope:dataframe:f.e

L input.r /^ L <- 2$/;" functionVar scope:function:f

.. TODO:

- other kinds

- operators for assignment, <-, <<-, ->>, ->, =

- illuminating duplicated tags

- fields (constructor, assignmentop)

- sub parsers

SEE ALSO

--------

ctags(1)